Drill point gauge



1D.Q.;.4,1951l QQCARLSON 2,577,228

DRILL POINT GAUGE Filed Feb. 17, 1950 2 SHEETS--SHEET l .ffarneys Dec. 4, 1951 Filed Feb. 17, 1950 C. C. CARLSON DRILL POINT GAUGE 2 SHEETS-SHEET 2 Innen for AMLLALX fag@ Patented Dec. 4, 1951 DRILL POINT GAUGE Clarence C. Carlson, Batavia, Ill., assigner to Burgess-Norton Mfg. Co., Geneva, Ill., a corporation of Illinois Application February 17, 1950, Serial N o. 144,686

8 Claims. (Cl. 33-201) This invention relates to improvements in drill point gauges of the kind designed to determine whether or not the web of a twist drill has been ground on center.

Twist drills, as they come from the factory, are usually formed at the cutting end with a coneshaped surface called the point and with two spiral grooves running along opposite sides of the' drill known as ilutes The metal column which separates the flutes is known as the web. 'I'his web is the main supporting column of the drill and gradually increases in thickness toward .the shank of the drill opposite the point. The two ilutes terminate at the point'n cutting edges or lips which are substantially parallel with each other and separated at the extreme tip end of the drill by a sharp edge called the dead center or chisel pointif This chisel point is usually formed at an angle which is slightly oblique. to

to the axis, and a certain clearance-with respect to `each cutting lip, to giveV the desiredr lcutting action. Commercial twist drill point grinders are available for pointing drills with the proper angles and clearances. In addition, however, itv is also necessary to thin the web each timea drill' is pointed back or sharpened to obtain the desired ease of penetration and wear. f l Y K operation is usually done by hand on'a relatively This thinning;`

thin, round riace emery wheel, which'is applied alternately along the inner spiral surfaces of the two utes, so as to thin down the web toward the chisel point and the cutting lips. 'Y

Different types of gauges have heretofore been employed for determining whether the point surfaces have been ground at the proper angle, and with the dead center or chisel pointon the dead center axis of the drill, but heretofore the drill` Y pointer has had to rely mainly upon his eyesight to determine whether or not the web thinning The object of the present inventionis to prio-l vide a gauge for determining whether or nottheA web has been ground on center, or how much off it might be.

A further object of the invention is to provideA a drill gauge of the character described, wherein the supporting parts of the gauge are relatively open so as to permit the operatorio observewhether or not the drill point is in proper regis- 2 tering relation with the critical parts of the gauge during testing.

Another object is to provide a gauge structure of the kind above described, which is readily adjustable for drills of different sizes.

Other objects and advantages of the invention will appear from time to time as the following description proceeds.

The invention may best be understood by reference to the accompanying drawings, in which:

Figure 1 is a plan view of a drill gauge constructed in accordance with my invention but with the off-center indicator omitted therefrom;

Figure 2 isa side view of the gauge shown in Figure 1 but with the off-center indicator4 mounted thereon; y

Figure 3 is a detailed section taken on line 3--3 of Figure 2;

Figure 4 is an enlarged end view of the gauge shown in Figure 2; v

Figure 5 is a fragmentary detailed section taken generally on line 5 5 of Figure 2 showing a drill in position for checking in the gauge;

Figure 6 is a detailed section taken generally on line G-'G of Figure 5; and

Figure 7 is a detailed section taken on line 1-7 of Figure 5.

Referring now to the details of the embodiment of my invention shown in the drawings, the gauge includes horizontal bed plate or frame IU which may be provided with supporting legs I I, I I. Two V-shaped supporting blocks I2 and I3 are adjustably mounted longitudinally of the bed frameA IQ to receive and support drills of varying lengths in horizontal alignment with said bed frame. In the form shown herein, one of the V-shaped blocks I2 has V-shaped drill supporting surfaces I 2a somewhat longer than the drill supporting surfaces I3a of the block I3. The block I2 is secured in place on the bed frame I0 by a threaded stem I4 extending downwardly through an elongated slot I6 formed centrally and lengthwise of the bed frame Ill, and having a knurled hand-nut I5 engaging the under face of said bed frame. The block I3 has a threaded stem I'I also passing through the slot I6 and with a nut I8 thereon. In the form shown, the knurled adjusting nut I8 of block I3 issomewhat larger than the adjusting nut I5 ofblock I2 since the latter block usually may remain in substantially the same position for most sizes of drills, whereas the block I3 may require more frecluent adjustment to accommodate drills of different lengths.

A third V-shaned supporting block ZI] is fixed at one end of the bed frame, having V-shaped supporting surfaces 20a, 20a in horizontal alignthe bed frame ii) in longitudinally spaced rela.=.-

tion to the fixed supporting block and consists essentially of an end block against which the point of the drill may haveseating engagement, and a calibrated gaugel member or. indi.- cator 26 fixed on an upright standard 2l secured to the end block 25.

The end block 25 is mounted;fervente-ar ad# l justment relative to the bed frame to accornmcj date the gauge means tot drills of various sizes. The end. block: 25 is suitably connected as. by cap screws 28 to a horizontally disposed. supporting. arm; 2.9 connected to,.and. herein formed integrally with, a block-'3.91 having dove-tailedconnection indicatedattll for vertical sliding adjustment along one side of the HiredsupportingY blockl. The vertical adjustment of. theblockV 3D, carrying arm 29 and end .block25, .is effected by an upright screw shafty 33 threadedthrough the block, 30` and having its lowerY end'journall'ed in a` laterally extendingY bracket 34. iixed. as by cap screws 35 to the botto-m face. of. the bed frame: Ill: (see Figurel.. .Thrust collarst andi Share. pinned onfthe-v screw shaft. 3.3. above and below the bracket 34. A; knurled thumb nutz is Xed to the upper end of theshaft. 3.3. for, manual. rotation of` the screwA shaft. 33;

The upright standard 2?, carrying the. gauge indicator 2F, is` horizontally'v adjustable. transversely of the end block 25 as byablock- MJ, .herein. formed integrally with` the lower endof the standard 21 and; having dove-tailed. connection indicated atv 4! for. horizontal sliding movement along the rear or outer iace` of the endbleck.

Adjustment of block 4d is controlled by ashait .f

43'- having one end threaded in the blocks. 4e and the other end journalled in the. outer end lor arrnA 29- with thrust collars M- and fi51- engaging opposite' sides of the latter armi. A knurled.

thumb nut i6`v` is xedon the extreme outerend of shaft 43" for manual'rotation of the latterf..

Referring now more speciicallyy todetailsk of th'e end block 25' and' itsfrelation to the gauge member 26, said end block is provided withtwo inwardly facing, generally upright bearing'facesf 459- and 'ilwhich'are disposedat an angle to each other corresponding to ther` conventional angle? to'which the conical endsurfaces of.' commercial drills are usuallyA ground; namely; at' 'angles of 5'9"1'to the axis ofA the-drill, or at 1:18?" to each other;A

The bea-ring faces eand 5:3 on. endblock-iz. are disposedin longitudinally-f centered alignment with the drill supporting blocks 2li, l2 and' i3, so asb to. receive the point' of" a drill: in seated'relation' therebetweenwhen a drill is laid' in horizontally centered position along the 2 sup-porting blocksZ, l2 and i3, and the end' block israised o'r' lowered into registering position with the drill point.

A horizontally ,disposed stop member- 55' p-rojects inwardly from one of the bearing faces of the end block 2551 As shown hereiny said" stop' member may be integral with a plate 55 secured as by cap screws 5l, 57 to the upper sur- 4 face of the end block 25. Said plate 55 has its inner edge cut to shape corresponding with the contour of the bearing faces i9 and 5G of the end block, excepting for the projecting stop member 55, the lower face of which forms a stop shoulder 59. The inner end 62) or stop member 55 terminates at a recess 58 formed in thefplate 5.5 in vertical alignment with an uprighttgroover 5.8tforrnedfr in. the end block 25 at the point of .juncture of the bearing faces 4Q and 59. Thus, the inner terminal edge 5t or the Astop member 55 terminates short oi the longitudina'l` center line orV Yaxis of the gauge, for

Y reasons that WHL-.presently appear.

YThe:gauge;meinb-:r or indicator 2% may be a conventional.; dial; type indicator having a movable control rod depending therefrom with a The' gauge` member 25 and its tip et ar.e.-mounted on the upright standard 2l so that the tip 55. projects downwardly within the recessedportion. 58. oi plate 5.6, for comparingthe relative depths of ther web surfaces of the drill at. theV extreme end. of the drill flutes..v The indicator on the gauge dial is preferably'set at zero Whenthe extreme. point oi. the gauge tip is in exact alignment with-the. stop shoulder 59. The gauge tip is, however,` free for limited longitudinal movement aboveandbelow its .zero point, as usual in indicating devices ofY this kind.

The usev and operation of the gauge may now be described as. follows 1.

As--willfbe seenlfrom Figures. 5. and. 6, a, drill indicated at 10. is laid on. and along the supporting blocks 20, I2andil3 and its conical point is moved.. endwise. into seated engagement with respect toY the uprightbearing faces, 9 .and 5) ofthe end block 25;. It may be necessary, as previously mentioned, to adjust the end' block 25 tov the proper height for this purpose. During such vertical adjustment, stop member 55 must be. positioned so that the stop shoulder 59 is brought into substantial, vif not precise, parallelism with .the face,.as shown in. Figures 6 and '7. This adjustment is readily effected, rst by providing a roughvertical adjustment of.. the end block relative to the drill point, andthen by rotating the drill point towardv the stop shoulder 59 until the cuttingflip Il is substantially parallel With said stop shoulder. Y Ay nal verticaladjustment ofthev end .block is-then made by thumb nut 38.-` to bring the cutting lipY HV into.. parallel engagement along and-beneath thestop shoulder 59, as shown inFigures6 and 7.. Y

While the drill andend block are being brought into Ycritical relative position, as shown. in Figures G--and 7 just described,l it will be understood that the tip 65 of theindicator gauge isrfree for Vertical. movementV closely adjacent the apex of the.- angle.I formed between bearingfacesv and or"Y thel end block so. that said gauge tip may ride upon the'upperfsurface ofthe cutting lip l withinthefinner terminalv edge of the stop member: duringA such` adjustment. The. extreme point-'ofthe gauge tip is preferably adjusted so' that: theA indicator. on'v thegauge dialzis zero when th'epointof' thes tip' is in exactalignmentwith the stop shoulder 59-onstop member 55. It will, therefore, be understood that; when the uppermost cuttinglip l l" is adjusted'into parallel engagement along and beneath the stop' shoulder 59, the gauge reading should be zero, 'assuming'of' course that thek cutting' lip continues substanti'ally straight to the point where thetip 65' engages said cuttinglipY closely 'adjacentvv the apex ofthe drill point'.

L As will be noted from Figure '7, however', the cutting'lip Il Vnormally ktends to curve upwardly and away from the true axis of the .drill at a point slightly oifset from said axis, that is to say from a point substantially above the upper end of the chisel point 13 of the drill, which isdisposed at a slight angle to the cutting lip 'Il and intersects the true axis of the drill. .For best results, therefore, the extreme point of the gauge tip 66 is adjusted so that it restsson the edge of the cutting lip directly above the upper .end of the chisel point at a point slightly oifset vfrom the drill axis in a direction toward the cutting lip 'll as clearly shown in Figures and 7.- With-this position of the gauge tip 66, any variation, plus or minus, from true parallelism between the cutting lip 1| and the stop shoulder 59 will be registered onV the dial of the Iindicator 26, For convenience, the indicator may be calibrated, as usual, in thousandths of an inch. l y

Once a plus or minus reading on the dial is ascertained for-the cutting lip 1I, the drill is then rotated by hand in its supports so as to bring the opposite cutting lip 12 into engagement beneath the stop shoulder 59. Then, without any vertical readjustment of the stop shoulder 59, a plus or minus reading of the gauge will immediately show by comparison. whether or not the two cutting lips are properly centered with respect to the drill axis. In other words, the comparative reading of the gauge in the two positions of engagement of the cutting lips with respect to the stop shoulder 59 will quickly indicate whether or notthe web has been equally thinned along the bottom of the two flutes where they terminate at their respective cutting lips, o r whether further thinning of the web is necessary in one or the other of vthe utes, to bring the two cutting lips into proper centered relation to the axis of the drill. Y

QIt may be` explained further that, although reasonable care should be exercised in the .initial setting of the end block so that the stop shoulder 59 is parallel with the rst cutting lip when brought into engagement therewith, yet some variation from exact-parallelism at this point may be permitted Without seriously affecting the comparative readings for the two sides of the web. For instance,if onlythe outer end of the cutting lip 'H is brought into actual engagement with the stop shoulder 59 leavingva small angle betweenV the inner end of this'lipV and the stop shoulder 59, a fairly accurate comparative reading can be obtained when the second lip 'l2 is rotated into engagement with the stop shoulder 59, because substantially the same amount of Aerror will be included in the readings for v,both positionsof the drill. Y

The gauge tip 66 is preferably formed with a terminal arcuate blade-like end 61 so as to aid said gauge tip in riding along the proximate surfaces of the drill while the latter is being advanced and rotated to position the cutting lips in their proper seated relation where the comparative readings are to be-taken. In the-'preferred form shown herein, the blade-like end` 61 is slightly wedge-shaped in cross section, shown in Figure 5, and said blade is turned at an angle to the axis of the drill which is slightly less than that of the proximate drill point surface. Thus,

in Figure 5, the blade is turned at an angle of approximately 40 to the drill axis. The thinner edge of the blade-like end 61 is continued to the extreme point of the tip for .engagement with the cutting lips of the drill while the wider edge of indicated at 68, to form a bearing engagement for proximate surfaces of the drill point, while the latter is being adjusted to reading positions in the gauge.

z' It will be'further observed that, by reason of the extended position of the end block 25 and supporting arm 29 with respect to the iixed supporting'block 20, there is ample space for the operator to observe whether the drill point is properly seated in the end block for the comparative gauge readings.

' Although I have shown and described certain embodiments of my invention, it will be understood that I do not wish to be limited to the exact construction shown and described, but that various changes and modiiications may be made Without departing from the spirit and scope of the invention as dened in the -appended claims.

I claim:

Y 1. In a centering gauge for the web at the point of a twist drill, a fixture including drill supportingv means affording rotation of a drill on its longitudinal axis, an end block spaced longitudinally of said supporting means having angularly disposed' abutment faces adapted to receive the pointed end surfaces of the drill in endwise seated relation therebetween, a stop member projecting from one of said abutment faces normally thereto and outwardly of the line of intersection formed by extending the planes of said abutment faces, and gauge means mounted on said end block having a gauge tip movable along and closely adjacent said line of intersection, for successive engagement with each cutting lip sub'- stantially at the chisel point of the drill when each such cuttinglip is engaged iiatwise with said stop member.

' .12. In a centering gauge for the web at the point of atwist drill, a xture including drill supportingv means alfording rotation of a drill on its longitudinal axis, an end block spaced longitudinally of said supporting means having angularly disposed abutment faces adapted to receive the pointed end surfaces of the drill in endwise seated relationtherebetween, a stop member projecting from one of said rabutrnent faces normally thereto and outwardly of the line of intersection formed by extending the planes of said abutment faces, means for adjusting said end block in a directioniparallel to said line of intersection, and gaugemeans mounted on said end block having a 'gauge tip movable along and closely adjacent said line of intersection, for successive engagement Ywith each cutting lip substantially at the chisel point of the drill when each such cutting lipfis engaged flatwise with said stop member.

- 3. In a centering gauge for the web at the point ofa twistdrill, a fixture including drill supporting meansV affording rotation of a drill on its longitudinal axis, an end block spaced longitudinally of 'said supporting means having angularly disposed abutment faces adapted to receive the pointed end surfaceswof the drill in endwise seated relation therebetween, a stop member projecting from one of said abtument faces normally thereto and outwardly of the line of intersection formed by extending the planes of said abutment faces, means for adjusting said end block in a direction parallel to said line of intersection, gauge` means mounted on said end block having a gauge tip movable along and closely adjacent said line of intersection, for successive engagement with each cutting lip substantially at the chisel point of the drill when each such cutting lip is; engaged'. flatwise`withf said; stop i member-z andlmeansforadjusting saidgauge tipatoxvaryingx reading: positions toward orsawayfA from-i said. stop member' transversely ofthe end. block.

4. In a centering gauge for the web atxtherpoint of 1a* twist drill, a-:xtureincluding-drill supporting means laiording: rotation off ardrill onpits'longia. tudinal` axis; .ani end block mounted adj acentsaidi supporting means having,r angularly-` disposedV abutment faces adapted to receive the pointed end surfaceszof the drill in endwise seated relation therebetween, a stop member projecting; from. onenof saidf abutment; faces`V normally. thereto and outwardly off thej line: of. intersection. formed by" extending the.planes=of:"said abutment faces, andV gauge means mounted on said endfblock having a; gaugetipmovable inraV path along. and closely, adjacent said line ofi'intersection, forfsuccessive engagement. with each cutting lipv substantially: at the chisel point of the drill when each such cutting lip is engaged flatwise with said stop member, said gauge tip comprising anarcuate bladeY member terminating in a. lip-contacting point, and said blade being turned. at an acute angle tothe axis of said drill point; with its4 lipcontactingpoint-1 extending towardV the stop member.

5. In acentering gauge for the'web at'the point off a twist drill, a` fixture including; drill support- Y ing means affording rotation of a drill on its longitudinal axis, an endV block mounted adja cent said supporting'meansrhaving' angularly disposed abutment faces adapted toV receive. the pointed'end surfacesrof thedrill in endwise seated relationgtherebetween, a; stop member projecting from'one of said abutment faces normally; thereto, and gauge means mounted on said end block hav'- ing a gauge tip movable in a pathv along and closely* adjacent the line of intersection of the extended planes of saidabutment faces, for successive engagement with each cutting lip substantially at the chisel point of the drill when each such cutting lip is engaged flatwise with said stop member, said gauge tip comprising an arcuate blademember tapered toward its end and terminating in a lip-contacting point, andsaicl blade beingturned at an acute angle to the: axis of said drill point with its lip-contacting point extending toward saidstop member.

6. In a centeringgauge for the web atthe; pointof a twistA drill, axture including drill supporting means aordingrotation ofra drill on its longitudinal axiaan end-block spaced longitudinally of said supporting means havingI angularly disposed abutment faces adapted toreceive,` the pointed end surfaces of; the: drill in endwisei. seated relation therebetween, a, stop member pro-.- jecting. from; one of said. abutmentY faces. outwardly of the line' of intersection formed. by extending the planes offsaid abutment' faces, having an elongated stop shoulder; disposed ina plane perpendicular to,v the lineY of' intersection, and: gauge means. mounted on said endv block hav-ing af gauge tip movable along and closelyadjacent said line of intersection, for successive engage-- ment with eachl cutting lip substantially: at: the;

chisel.'pointfofthefdrill when eachf such-cutting lipfisrcngagednatwsef with4 said stop; member.

' 'lilna centering -gaugefor the webat the point?y of a twist'drill, a;l xtureaincluding;drillsupport-m ingV means affording: rotation of4 adrill onA itsv longitudinal axis;,an end;blocl spaced longituf( dinally of 'said supportingmeans having angularly disposed-.abutment faces adapted to receive: theV pointed end surfaces ofthe drill in endwise seatedi relation therebetween, a. stop member projecting froml onev of said abutment faces outwardly of the line'ofintersection formed by extendingA theplanes of said abutmentfaces; having an clon-k gated" stop shoulder disposed in a plane ,perpen dicular` to the line of intersection, means for adjusting said'end' blockv in ardirection` parallel with' said line of"intersection'; and: gauge means mountedA on saidV endblock having agauge tip` movable a path closely adjacent said line of' intersection, for successive engagementwith each cutting lip substantially at thechisel pointfof the drill when each suchlcutting lipl isengaged flat--n wise with saidv stop member.V

8l In a centering gauge for thek webatl the pointof a twist drill; aixture including drill supporting means affording rotation of'a drillon its. longitudinal axis,V an end blockj spaced-longitudinally ofk said supporting-meansv having angu-Y larly disposed abutment faces adaptedl to receive they pointed end surfaces'of the-drill in endwise' seated relation therebetween, a stop memberl projecting from one of said abutment faces outwardly ofthe line of intersection'formed by-exf tending the'planes-of'said abutmentfaces, having anelongated=stop-shoulder disposed" in aplane perpendicular to thel 1ine-of"intersection',- meansl for adjusting said end' block-in Vadirection parallel with said line-of intersection, gauge means mounted on said end blockA havingy a gauge' tip movable ina path Aclosely adjacent said linei ofintersection, for successive engagement with each cuttinglip substantially at the chisel point of the drill when each such cuttinglipis engaged flatwisewith said stop member, andgmeans fory adjusting said vgauge tip to varying reading; positions toward and away Yfrom said stop member transversely` of the end block.

. CLARENCE C. CARLSON.

j REFERENCES CITED` The following-v references are of record;` in the le of this patent:

UNITED STATES PATENTS f Number Name Date 996,503 Minges V A, A ,June 27,1911' 1174,009 Hj'orth Febr.v2,9, 1915v 2,337,819 Hofmann4 V k v Dec.v 28, 19,43

FOREIGN PATENTS Number Country Date 219,184A Switzerland May- 1, 1942 OTHER. REFERENCES .AmericanMachnists May` 22.19305 pages 838, 839. 

